Substantial amounts of sour natural gas are currently being produced from natural gas wells, oil wells (for example, as associated gas), and from natural gas storage reservoirs that have been infected with hydrogen sulfide-producing bacteria. The presence of hydrogen sulfide and other sulfur compounds in fuel and other gases has long been of concern for both the users and the producers of such gases. In addition to the corrosive and other adverse effects that such impurities have upon equipment and processes, noxious emissions are commonly produced from combustion of the natural gas as a result of oxidation of the sulfur compounds. The resulting sulfur oxides can be a major contributor to air pollution and may have detrimental impact upon the environment. Increasingly stringent federal and state regulations have accordingly been promulgated in an effort to reduce or eliminate sulfurous emissions, and a concomitant interest exists in efficiently removing from natural gas and the like the hydrogen sulfide that comprises a significant precursor of noxious emissions. In addition, one method of disposing of hydrogen sulfide has been to convert it into solid sulfur, for storage. Due to environmental and aesthetic concerns, many countries are now outlawing the formation of such sulfur stores.
Enhanced Oil Recovery (EOR) may be used to increase oil recovery in fields worldwide. There are three main types of EOR, thermal, chemical/polymer and gas injection, which may be used to increase oil recovery from a reservoir, beyond what can be achieved by conventional means—possibly extending the life of a field and boosting the oil recovery factor.
Thermal enhanced recovery works by adding heat to the reservoir. The most widely practiced form is a steamdrive, which reduces oil viscosity so that it can flow to the producing wells. Chemical flooding increases recovery by reducing the capillary forces that trap residual oil. Polymer flooding improves the sweep efficiency of injected water. Miscible gas injection works in a similar way to chemical flooding. By injecting a fluid that is miscible with the oil, trapped residual oil can be recovered.
Referring to FIG. 1, there is illustrated prior art system 100. System 100 includes underground formation 102, underground formation 104, underground formation 106, and underground formation 108. Production facility 110 is provided at the surface. Well 112 traverses formations 102 and 104, and terminates in formation 106. The portion of formation 106 is shown at 114. Oil and gas are produced from formation 106 through well 112, to production facility 110. Gas and liquid are separated from each other, gas is stored in gas storage 116 and liquid is stored in liquid storage 118. Gas in gas storage 116 may contain hydrogen sulfide, which must be processed, transported, disposed of, or stored.
Co-Pending Patent Application Publication U.S. 2006/0254769 discloses a system including a mechanism for recovering oil and/or gas from an underground formation, the oil and/or gas comprising one or more sulfur compounds; a mechanism for converting at least a portion of the sulfur compounds from the recovered oil and/or gas into a carbon disulfide formulation; and a mechanism for releasing at least a portion of the carbon disulfide formulation into a formation. Publication U.S. 2006/0254769 is herein incorporated by reference in its entirety.
There is a need in the art for improved systems and methods for processing, transportation, disposal, or storage of hydrogen sulfide from a liquid and/or gas. There is a need in the art for improved systems and methods for processing, transportation, disposal, or storage of sulfur from a liquid and/or gas. There is a further need in the art for improved systems and methods for enhanced oil recovery. There is a further need in the art for improved systems and methods for enhanced oil recovery using a sulfur compound, for example through viscosity reduction, chemical effects, and miscible flooding. There is a further need in the art for improved systems and methods for making sulfur containing enhanced oil recovery agents.
In addition, carbon disulfide is a common chemical with applications ranging from use as a commercial solvent for the production of rayon, to a raw material for the production of agricultural insecticides. The carbon disulfide manufacturing process involves the purchase and transport of both solid sulfur and natural gas (or another carbon source), often from long distances, to the manufacturing site and produces carbon disulfide at very high purity. These two factors—the high purchase and shipping costs of the raw materials, and the high purity of the final product—result in a relatively high production cost for carbon disulfide.
The manufacturing process for converting sour gas into solid sulfur involves a solvent unit to first remove hydrogen sulfide, other sulfur compounds, and contaminants such as carbon dioxide from the natural gas stream, followed by a Claus unit to convert the hydrogen sulfide into sulfur, which is then allowed to solidify prior to transport or transported as a liquid. The manufacturing process for manufacturing carbon disulfide, on the other hand, entails the heating, melting, and vaporization of solid or liquid sulfur and reacting its vapors with heated natural gas or another carbon source.
There is a need in the art for improved systems and methods for carbon disulfide manufacturing. There is a need in the art for improved systems and methods for more energy efficient carbon disulfide manufacturing. There is a need in the art for improved systems and methods for removing carbon disulfide from a reservoir at the conclusion of an EOR process.